This invention relates to an apparatus for handling flat articles, such as an envelope and a postcard, and more particularly, to a flat article feeding apparatus which successively feeds flat articles from a stacker, one by one.
In a conventional flat article feeding apparatus, a suction chamber is arranged at a position confronting flat articles which are accumulated in a stacker. An endless suction belt, having pierced holes, is driven around the suction chamber to pick up the flat articles, one by one, from the stacker. The flat article thus picked up is caught in the nip and pinched between a pair of transfer belts aligned with and confronting the output end of the suction belt.
The construction of such a conventional flat article feeding apparatus is schematically disclosed, for example, in U.S. Pat. No. 3,604,702, and particularly in its FIG. 2. In the disclosed feeding apparatus, an entrance space at the front of the pair of transfer belts is enlarged to ensure receiving the flat articles as they are delivered from the suction belt. Such a structure of the transfer belts is advantageous in that, even if there is a bent tip on the fed flat article delivered from the suction belt, the fed flat article can be pinched securely between the pair of the transfer belts.
The conventional flat article feeding apparatus, however, is defective in the following respects. In general, the suction belt and transfer belts are driven at a certain constant speed at which the flat article is transferred. On the other hand, as described above, in order to pinch the fed flat article accurately, the entrance space of the transfer belts is enlarged. For example, one of the pair of transfer belts is opened at a certain angle with respect to the transfer direction as shown in FIG. 2 of U.S. Pat. No. 3,604,702. Assuming that the transfer speed is V and the angle if .theta., of the one opened belt at the entrance of the transfer belt, a speed of transfer direction component of the opened belt is represented by V cos .theta., which is surely smaller than V. As a consequence, when the flat article is delivered from the suction belt driving at the transfer speed V, and if its leading tip end is bent, and the tip collides against the opened belt of the transfer belts, a large pressure is exerted on the leading end or tip of the flat article due to the difference between its speed V and the opened belt's speed V cos .theta. in the transfer direction component. This is apt to cause a mutiliation of the article, a misoperation, and a jam.